IGCSE Biology - Reproduction

Oestrogen thickens and rebuilds the lining of the uterus, preparing it for implantation, whilst developing blood vessels and inhibiting the release of follicle stimulating hormone.

Progesterone is secreted by the corpus luteum and the placenta.  It maintains the thickened uterus lining and keeps it well supplied with blood, preparing it for implantation and preventing the release of follicles.

The amnion secretes the amniotic fluid, which cushions and supports the fetus whilst allowing it to move freely and maintain a constant temperature.

The placenta connects the fetus to the wall of the uterus.  The…